Learning the Lobo, and having some difficulties

[thest...@gmail.com]

I just need some general advice for where to look for information and general things people have learned when using the Lobo Mill.

I am planning on using the Lobo to cut some sheet metal samples for my lab. I am turning here as I don't have anyone in my area who has experience with this software. However, I need to learn how to get the system to work before I can do more.

I have the system setup and linked up to my computer. I found that my antivirus Avast does some weird Ghost Shield thing that made it crash, so I had to disable it. I have gotten the axes to move their full range.

First, I damaged my table slightly. What occurred was I ran the homing procedure and it lowered the spindle into the table (spindle was off) then it dragged the head in the X and Y, leaving a mark on the surface. I have found it always lowers the head in the Z then moves the other axes. It is supposed to do that? What is the point of lowering the Z by ~1" and have it collide, then moving the other axes so it scrapes?

I have been having fun testing my own G-Code, but (I assume this is a common goal) I want to be able to rapidly create parts from designs. I am proficient with Blender, Inkscape, Autodesk Inventor, Soldiworks (don't have a licence anymore), and AutoCAD. I have been having a blast with printing things off with my RepRap 3D printer with taking an .STL file, having a software to write the G-Code, then executing.

I am wondering what software is a good G-Code maker for the Lobo. I have seen, and experimented with PyCAM, but I don't know how to setup the program correctly for the Lobo.

In the end, there are three operations I want to use a Lobo for:
- Making sheet metal samples out of aluminium for research

- Engraving copper sheets with a bristle brush for printmaking. Scraping copper leaves groves for ink. The harder the brush is pushed into the material, the more ink it can hold. By changing the z-height, I should be able to take a picture and turn it into an engraving image for printing. It doesn't need to be copper, but it is commonly used.

- Carving wood for various parts.

Anyway, if I could get some help learning where to start, that would be great. I am currently just writing out the G-Code manually, which is slow. I have it running circles and going to points as desired.

Nick

[Jeff]

Nick,

On the homing, it should raise the spindle rather than lower it - it should not be crashing into the table.  Because all the motors are pre-wired, the only way I think that this could happen is if 1) you have changed the something in the PSCNC.INI file or 2) you have the motors plugged into the wrong connectors on the controller board.  When you use the JOG buttons in the PSCNC program, make sure that the X, Y and Z axes all move in the correct direction when you click on each of the jog buttons.  (The included file PSCNC.PDF has a diagram showing the orientation of the axes.)

Regarding CAM programs to generate G-Code, I mostly use CamBam.  You can download a demo version that will let you run it 40 times.  Other than setting the mode to inches, the default post-processor does a good job of generating G-Code for the Lobo CNC machine.  I put up a short tutorial video (see http://lobocnc.com/gallery.html) on how to go from a DXF file to a G-Code program using CamBam.

Jeff

[Norman Brewer]

I started with CamBam and found it pretty easy to use and a good introduction to both CAD and g-code.  I also did several designs in CorelDraw and exported DXF files to CamBam for creating the g-code.  I used F-Engrave (free) to create some V-Carved monograms for use in wooden music boxes.  All of these programs have a substantial learning curve, and on top of that there is a lot of learning to do about what the basic hardware and router can do.  I recently moved to BobCad based on what one of my friends has been able to with it using a commercial CNC milling machine.  BobCad can do V-carving and 3-D CAD in one package, and if you are persistent you can get a decent package for a fraction of the retail price.  I have a working BobCad post processor for PSCNC which I can provide if anyone wants it.  BobCad gives you a lot of control over the g-code that gets produced by the post processor, so you can fine tune the output for PSCNC.

 

One thing I have learned is to make a trial cut on scrap or MDF before making a part for the first time.  I almost wrecked the top of a music box when the g-code produced by F-Engrave caused a major problem in PSCNC.  Fortunately, I was cutting scrap at the time so no harm was done.  I have also had unexplained "crop circles" appear in BobCad output and other unexplained events.  I also managed to route a couple of holes in my table until I got the tool height compensation of BobCad turned off in the post processor.

 

I also have two simulators to test programs created by BobCad.  The internal BobCad simulator apparently works off some internal representation of the CNC program you create.  If it shows an issue, then for sure there will be a problem if you try to cut the part.  The simulator doesn't really run the g-code, so even if the BobCad simulator looks good, there can still be an issue with the g-code.  The Predator g-code editor that came with BobCad has a back-plot capability and seems to emulate PSCNC fairly well, so it typically shows any g-code problems like the crop circles that the BobCad simulator doesn't see.

 

So far I have done quite a few 2.5D projects, and am working on my first 3D design in BobCad.  3D has been a lot harder than I anticipated. 

[Jeff]

Thanks for the info on BobCad.  I had forgotten about BobCad - many years ago it used to be the only budget CAM system around.  Now, it looks to be a little less budget.  When you say that with persistence you can get a decent package at a fraction of the retail price, how small a fraction?

-Jeff

[Norman Brewer]

I paid about $400 for their mill express package.  The latest version is V26.  There is a "BobCad after dark" site that has a lot of videos on it, and a lot of info on various forums.  I get occasional crashes, especially while doing 3D drawing, but the problems may be self-made.  I don't really like the deep discount marketing scheme they use with inflated retail prices and special sales, but you can try the software out for a limited time with no committment.  The V-Carving handles some fonts better than F-Engrave did, and the CAD drawing capabilities are fairly good.  CamBam has some features like tabs that you have to pay extra for in BobCad.  I still have a lot to learn.

 

[Nicholas Andreae]

I learned things today about the mill

I have been having fun making things on the Lobo. Mostly wood, but some aluminum. Today I pushed the machine to the limits, and took it a little too far. I have a 5" x 5" x 1.75" block of aluminum. Goal was to mill both sides flat. I got that to 0.003", which I was happy about. Used a 7/16" end mill and had it on the Makita RT0700C with a speed of 3. I think that is at 10,000rpm at that speed, which is way beyond what I want to run it at, but it works well.

The next operation was a pocket 1" deep, 5" wide. I wanted to drill a 1/4" hole in the middle thought so that the end mill would be okay plunging, but I didn't want to remove it from the frame. So I put the 1/4" bit into the router and dropped the speed to 1. Started drilling.

It sounded bad. Really bad, but it was drilling well. I was going, "okay, sounds bad, frame is weak, not doing too well on the frame, but hole is drilling." Everything was cool until smoke rose from the router.

Sigh. Learning. No drilling aluminum on the Lobo.

Off to get a new router tomorrow.

[Jeff]

Wow, you smoked a router!  I'm guessing that the severe chatter was driving the speed control circuit nuts.  Yeah, I never drill with the high-speed router spindle except for really tiny (<1/16") diameter holes.  Drilling generally likes to be done at much lower speeds.  BTW, I think the "1" speed setting on the Makita router corresponds to about 10000 RPM, which is still way too fast for most drilling.

[Nicholas Andreae]

Here it is after the job. It took 3 hours solid of running to do the job

[Jeff]

Impressive.  Looks like you might win the award for the biggest chunk of aluminum hogged out on a Lobo CNC machine.